LS 430 Exhaust System

DaKa · January 11, 2020

Last year my 2001 LS430 scraped through its MOT on emissions, its due for renewal at end March 2020, There is a warning light on the dash and the error code has pointed to the front catalytic converters, both sides of the down pipes losing efficiency. The exhaust is otherwise in great condition as I replaced from the mid-rear sections with aftermarket import spares about 18 months ago. I do about 3,000 miles a year and buying a new car isn't excatly environmentally friendly even if its an EV in my opinion.

I've been trying to source new CATs, in fact a whole front the back exhaust system, but aside from one UK advert for an exhaust specialist in Leeds, there appears to be no new spares available.

I'm prepared to spend a reasonable amount here, but I can't be silly as the value of the car is limited - I'm thinking £800-1000 maximum, if I'm being practical.

The only thing I can find is a megaflow system from USA, but its not clear if the front CATs are included (I think not) or, skipped by this system or, you have to buy these separately. It would be mad to buy/import the item on the link below only to find out you still need to purchase left/right front CATs.

Does anyone have a suggestion better than the link below, as I will likely need to scrap my car which otherwise is running perfectly and I would be sad to lose for this reason!

https://www.ebay.co.uk/itm/Magnaflow-Conv-DF-01-06-Lexus-LS430-4-3L-Rear/382078484113?_trkparms=aid%3D555021%26algo%3DPL.SIMRVI%26ao%3D1%26asc%3D20190711100440%26meid%3D9ebf5daff6e24c448f35372bcc2fdb78%26pid%3D100752%26rk%3D1%26rkt%3D11%26mehot%3Dpf%26sd%3D114046409240%26itm%3D382078484113%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100752.m1982

Do I have any alternative suggestions from members - has anyone else been in the same position and found a solution?

ambermarine · January 11, 2020

The system they are offering contains a cataytic converter which serves both banks, if they have designed it for a LS430 it must be a fit in terms of O2 sensers etc.

Perhaps an email asking them the question.

The-Acre · January 11, 2020

Is it worth trying lexussparesdirect direct for used cats? Could it also be another issue, ie o2 sensors? It may be worth getting the codes read on a better reader.

MLW · January 11, 2020

What was the exact error code?

DaKa · January 12, 2020

I've inadvertently cleared the error codes before reading them on my LS430 (sorry its been a while since I used the machine and should have read the instructions again) so the engine management light is now off.

As soon as its back, normally after 10-15 minutes driving, I'll read again.

It was very clear from memory, left bank catalytic converter losing efficiency, followed by same message for right bank.

I will call megaflow USA on Monday, as I'm thinking although it may have a more efficient mod section CAT, without the front 2 x CATS, would the sensors mean the engine light would remain - this is an MOT failure nowadays as any engine management warning light on is an MOT fail.

BigBoomer · January 13, 2020

I had a left bank efficiency code recently.
It was caused by a crack in the middle exhaust left side where it bolts to the headers/CAT.
I had an exhaust specialist replace that whole section (he kept the CAT after the 2 sides join up) for £150.
Check your codes. Mine was 430 or 420 (one is left, the other right) and both mean there is a leak in the middle section, or else a leak where they join the front section.
The primary CATs should be good for the life of the vehicle, unless you ran some diesel mixed with petrol or leaded fuel through the engine.

DaKa · January 18, 2020

Thanks George, I'm interested in your comments as I fo get a warning for both sdies.

I guess that I'm not sure exactly what you mean by a leak in the middle section? The manifold downpipes from both sides connect to their respective CATs, then after the sensors, the pipes bend in towards the middle section and another box (is this another CAT or just silencer?).

Are you are suggesting where the pipes join together before the mid-section box to look for leaks in this area?

The cost of replacement Left/Right CATs in circa £600 minimum for USA imports, so it would be nice to know the originals should still be efficient. I can't see much change out of £1000 here if I buy the megaflow above and need new CATs also!

DaKa · January 19, 2020

Having rest the rror codes it took about 90 minutes driving before the warning engine light appeared again.

In fact I made an assumption both banks as I had 1/2,/2/2 and assumed one was left and one right, but in fact both error codes relate to BANK2 as shown.

Does anyone know what side BANK2 means?

cruisermark · January 19, 2020

HI

Bank 1 is passenger side - Bank 2 is driver side

rich1068 · January 19, 2020

Assuming the cats are on the way out rather than the exhaust having a hole in it, couldn't this be *ahem* cured using sensor spacers?

And if you do need an exhaust the specialist in Leeds you mention early on in this thread is probably Tony Banks and definitely gets a :thumbsup: from me and quite a few others on here.

ScottC · January 20, 2020

Well the sensor spacers will fool the electronics into thinking the cats are working okay, so no fault light on the dashboard.

However the car still has to pass the emission test at the MOT centre☹️

I would check the Y pipe for holes.

ScottC

rich1068 · January 20, 2020

Of course. Silly me. Concentrating too much on the dash lights.

BigBoomer · January 20, 2020

Exact same error that I had. Take it to see Dean @ Pipecraft and they will sort it out for ya.
That error is caused by exhaust gases leaking out between the upstream and downstream lambda sensors.
Because of that the system assumes that the Primary CAT is not performing as it should.
The error can be caused by a split gasket where the middle (Y) exhaust section bolts to the headers/Primary CAT.
It can also be caused by a crack in the flange that bolts the headers/middle together.
Mine was blowing loud enough to hear it, but I've heard of others where the only indication was the error code.

DaKa · January 20, 2020

Thanks George - I will take it back to pipecraft for another assesment with my new found knowledge.

DruLS · January 26, 2020

My last LS430 was throwing codes for the CATs and the O2 sensors. They were actually fine, but as the exhaust was leaking it was throwing out those codes.

Instead of going to Lexus I had a full stainless steel catback made up for it with a third cat delete. I used Tony Banks Exhausts in Leeds and they did a top notch job. Just over £500 and they did it in just a few hours. They stock cats too so might be worth getting them to fit their own if you need them, instead of trying to source and fund genuine ones. I imagine Lexus would charge more and a regular steel exhaust will be prone to corrode and rust again. They'll build it however you like so you can have it quiet as stock if you'd like. I opted to have it just a little louder. It was still quiet, especially inside the cabin but sounded just a little deeper and actually sounded like a V8 should.

DaKa · March 1, 2020

Just an update.

I still have the error code, but was able to reset/clear it before the MOT - the engine management light stays off for 1-2 hours running before coming back on.

As you probably know warning lights on the dash are now an MOT failure, so had to do this. The MOT was due 2nd April, so I thought I would try early so as to allow time for the new exhaust parts from USA if needed.

Anyway, it passed, I've got myself another years MOT the emmissions were not a problem.

I'd actually put it in for the test a week too early, as I thought you could do it 6 weeks before, but was actually only 28 days.

I'm really pleased, but will likely take my time to get the parts needed for later in the year when I have more time to get them fitted..